From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 233DC6B0033 for ; Sun, 15 Oct 2017 03:50:39 -0400 (EDT) Received: by mail-pg0-f72.google.com with SMTP id b192so4268051pga.14 for ; Sun, 15 Oct 2017 00:50:39 -0700 (PDT) Received: from EUR02-HE1-obe.outbound.protection.outlook.com (mail-eopbgr10065.outbound.protection.outlook.com. [40.107.1.65]) by mx.google.com with ESMTPS id g1si2669071pgc.3.2017.10.15.00.50.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 15 Oct 2017 00:50:37 -0700 (PDT) Subject: Re: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP_CONTIG) support References: <20171012014611.18725-1-mike.kravetz@oracle.com> <20171012014611.18725-4-mike.kravetz@oracle.com> <20171012143756.p5bv4zx476qkmqhh@dhcp22.suse.cz> <20171013084054.me3kxhgbxzgm2lpr@dhcp22.suse.cz> <20171013152801.nbpk6nluotgbmfrs@dhcp22.suse.cz> <20171013154747.2jv7rtfqyyagiodn@dhcp22.suse.cz> <20171013161736.htumyr4cskfrjq64@dhcp22.suse.cz> From: Guy Shattah Message-ID: <752b49eb-55c6-5a34-ab41-6e91dd93ea70@mellanox.com> Date: Sun, 15 Oct 2017 10:50:29 +0300 MIME-Version: 1.0 In-Reply-To: <20171013161736.htumyr4cskfrjq64@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Christopher Lameter Cc: Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Marek Szyprowski , Michal Nazarewicz , "Aneesh Kumar K . V" , Joonsoo Kim , Anshuman Khandual , Laura Abbott , Vlastimil Babka On 13/10/2017 19:17, Michal Hocko wrote: > On Fri 13-10-17 10:56:13, Cristopher Lameter wrote: >> On Fri, 13 Oct 2017, Michal Hocko wrote: >> >>>> There is a generic posix interface that could we used for a variety of >>>> specific hardware dependent use cases. >>> Yes you wrote that already and my counter argument was that this generic >>> posix interface shouldn't bypass virtual memory abstraction. >> It does do that? In what way? > availability of the virtual address space depends on the availability of > the same sized contiguous physical memory range. That sounds like the > abstraction is gone to large part to me. In what way? userspace users will still be working with virtual memory. > >>>> There are numerous RDMA devices that would all need the mmap >>>> implementation. And this covers only the needs of one subsystem. There are >>>> other use cases. >>> That doesn't prevent providing a library function which could be reused >>> by all those drivers. Nothing really too much different from >>> remap_pfn_range. >> And then in all the other use cases as well. It would be much easier if >> mmap could give you the memory you need instead of havig numerous drivers >> improvise on their own. This is in particular also useful >> for numerous embedded use cases where you need contiguous memory. > But a generic implementation would have to deal with many issues as > already mentioned. If you make this driver specific you can have access > control based on fd etc... I really fail to see how this is any > different from remap_pfn_range. Why have several driver specific implementation if you can generalize the idea and implement an already existing POSIX standard? -- Guy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org